The goal of the Program Project is the development of a quantitative model for the objective evaluation of the clinical impact of picture archiving and communication systems (PACS). Diagnostic accuracy, efficiency, satisfaction, cost, and selected outcomes will be measured prospectively at three clinical sites: an emergency department, a medical intensive care unit, and surgical intensive care unit. An iterative design of data collection cycles interspersed with interventions is used to facilitate the evaluation of a rapidly changing technology. The first project develops an index of diagnostic value that combines diagnostic accuracy and the efficiency of information acquisition. Methods of estimating accuracy by using observer agreement will be studied. The index will be part of the effectiveness analysis. The second project studies how various PACS implementations influence the effectiveness of patient care. Mathematical models will be developed to simulate the diagnostic imaging and information delivery process. The simulations will provide data about the operation of the PACS under hypothetical situations and will help identify opportunities for improvement. The third project studies the effective use of PACS workstation in a clinical environment. It will concentrate on the timely acquisition of reports and images. The fourth project develops a model for the evaluation of the clinical and economic outcomes of PACS. This project will bring together the effectiveness measures from the other projects and integrate them into a cost-effectiveness model. These projects will provide not only useful information about PACS but also a model methodology for evaluating a rapidly emerging information based technology.